Ceramic honeycomb substrates and honeycomb filters for mobile exhaust systems are known. Square and rectangular honeycomb cells are generally made via extrusion. Particulate emissions in exhaust gas from diesel engines are typically handled by wall flow honeycombs with low thermal expansion materials such as cordierite or aluminum titanate based materials. The commercial products have generally straight, axially aligned channels with uniform cross-sections with plugs in alternating checker board patterns on the ends of the honeycomb pieces to force the exhaust gas through the cell channel walls.